ACS Earth and Space Chemistry最新文献

{"title":"Infrared Spectroscopy of Neutral and Cationic Sumanene (C21H12 & C21H12+) in the Gas Phase: Implications for Interstellar Aromatic Infrared Bands (AIBs)","authors":"Pavithraa Sundararajan*,&nbsp;Piero Ferrari*,&nbsp;Sandra Brünken*,&nbsp;Wybren Jan Buma,&nbsp;Alessandra Candian and Alexander Tielens,&nbsp;","doi":"10.1021/acsearthspacechem.4c0039310.1021/acsearthspacechem.4c00393","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00393https://doi.org/10.1021/acsearthspacechem.4c00393","url":null,"abstract":"<p >Polycyclic aromatic hydrocarbons (PAHs) are known to be omnipresent in various astronomical sources. Ever since the discovery of C₆₀ and C₇₀ fullerenes in a young planetary nebula in 2010, uncovering the reaction pathways between PAHs and fullerenes has been one of the primary goals in astrochemistry. Several laboratory studies have attempted to elucidate these pathways through experiments simulating top-down and bottom-up chemistry. Recently, indene (c-C₉H₈, a fused pentagon and hexagonal ring) has been detected in the TMC-1 molecular cloud. This is a significant finding since pentagon-bearing PAHs could be key intermediates in the formation of fullerenes in space. Spectroscopic studies of pentagon-bearing PAHs are thus essential for their detection in molecular clouds, which would eventually lead to unraveling the intermediate steps in PAH’s chemistry. This work reports the infrared (IR) spectra of both neutral and cationic sumanene (C₂₁H₁₂ and C₂₁H₁₂⁺): a bowl-shaped PAH containing three pentagon rings. Apart from its relevance for furthering our understanding of the chemistry of PAHs in an astronomical context, the presence of three sp³ hybridized carbons makes the vibrational spectroscopy of this molecule highly interesting also from a spectroscopic point of view, especially in the CH stretching region. The experimental IR spectra of both species are compared with quantum chemically calculated IR spectra as well as with the aromatic infrared bands (AIBs) of the photodissociation regions of the Orion Bar obtained using the James Webb Space Telescope (JWST).</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"898–910 898–910"},"PeriodicalIF":2.9,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00393","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photosensitized Reactions in Atmospheric Water: Triplet State Models Molecules, Reactivity, and Impact on the Carboxylic Acids and Amino Acids Fate","authors":"Marie Bretonniere,&nbsp;Mohamed Sarakha,&nbsp;Guillaume Voyard,&nbsp;Christian George and Marcello Brigante*,&nbsp;","doi":"10.1021/acsearthspacechem.5c0002610.1021/acsearthspacechem.5c00026","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00026https://doi.org/10.1021/acsearthspacechem.5c00026","url":null,"abstract":"<p >Recent studies have demonstrated that new reactions can be initiated by the irradiation of organic compounds in the atmospheric aqueous phase. In this medium, these photosensitized reactions represent an important, still understudied pathway affecting the composition of tropospheric organic matter. In this work, we investigated the photoreactivity of vanillic acid (VA) and 2-benzoylbenzoic acid (A2BB), as relevant proxies for sources of triplet excited states (VA* and A2BB*). Experiments conducted under various pH conditions revealed different reactivities toward molecular oxygen which is an important source of singlet oxygen with rate constants <i></i><math><msubsup><mrow><mi>k</mi></mrow><mrow><mrow><mi>t</mi></mrow><mrow><mi>r</mi></mrow><mrow><mi>i</mi></mrow><mrow><mi>p</mi></mrow><mrow><mi>l</mi></mrow><mrow><mi>e</mi></mrow><mrow><mi>t</mi></mrow><mrow><mo>,</mo></mrow><mrow><msub><mrow><mn>3</mn></mrow><mrow><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></msub></mrow></mrow><mrow><mrow><mo>″</mo></mrow></mrow></msubsup></math> ranging from 6.35 × 10⁸ to 4.31 × 10⁹ M^–1 s^–1 for VA* and A2BB*. The reactivity with short-chain carboxylic acids and amino acids, which are regularly found in the atmospheric aqueous phase, was also studied. Rate constants of these reactions varied from less than 10⁷ to 7.1 × 10⁹ M^–1 s^–1, suggesting that the reactivity with triplet excited states has to be considered important in some cases, in competition with that of the hydroxyl radical. In addition, the transformation of carboxylic acids and amino acids induced by triplet excited states was investigated, providing insights into the reactivity of these states and future consideration of the transformation pathways into atmospheric chemistry models.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"944–951 944–951"},"PeriodicalIF":2.9,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genesis of Clay Rock-Type Rare Earth in the Southwest of the Yangtze Block","authors":"Xinzheng Li,&nbsp;Ruidong Yang* and Xiaorui Wang,&nbsp;","doi":"10.1021/acsearthspacechem.4c0034710.1021/acsearthspacechem.4c00347","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00347https://doi.org/10.1021/acsearthspacechem.4c00347","url":null,"abstract":"<p >In the weathering crust of the Emeishan basalt in northwestern Guizhou, significant amounts of rare earth elements (REEs) are present. However, there has been limited research on kaolinite clay rocks formed by the transport and deposition of kaolinite derived from basalt weathering to coastal areas. This study focuses on the weathering crust of the basalt in the Nayong area of Guizhou, conducting mineralogical and geochemical investigations. The results reveal that the weathering crust in the Nayong area is rich in chlorite, quartz, anatase, and kaolinite. Geochemical analysis indicates that the weathering crust contains high concentrations of rare earth elements (108.75–903.03 × 10^–6), primarily originating from the Emeishan basalt. These REEs were released through weathering and transported by rivers to coastal areas for deposition. The Th/Sc vs Zr/Sc and La/Yb vs ΣREE diagrams, along with the significant variations in δEu (0.58–1.69) and δCe (0.87–1.18), suggest that the enrichment of REEs was accompanied by the incorporation of alkaline volcanic ash and may have been influenced by hydrothermal alteration in later stages. According to this study’s research results, it is proposed that the lower part of the weathering crust is in the element accumulation stage, the middle part is in the element leaching stage, and the upper part is in the element accumulation stage.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"829–843 829–843"},"PeriodicalIF":2.9,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hot Sulfur on the Rocks: The Reaction of Electronically Excited Sulfur Atoms with Water in an Ice-Surface Model","authors":"Gabriella Di Genova*,&nbsp;Jessica Perrero,&nbsp;Marzio Rosi,&nbsp;Cecilia Ceccarelli,&nbsp;Albert Rimola* and Nadia Balucani*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0035110.1021/acsearthspacechem.4c00351","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00351https://doi.org/10.1021/acsearthspacechem.4c00351","url":null,"abstract":"<p >In this contribution, we present a theoretical investigation of the reaction involving atomic sulfur in its first electronically excited state, ¹D, and H₂O on an ice-surface model. This study is motivated by the work of Giustini et al. (<i>ACS Earth Space Chem.</i>, <b>2024</b>, <i>8</i>, 2318), which indicated a strong effect of the presence of four additional water molecules in the S(¹D) + H₂O reaction compared to the pure gas-phase case. Our simulation treats the long-range interactions (H-bonds and dispersion forces) with the ice water molecules in a much more realistic way being based on the use of a cluster of 18 water molecules, thus overcoming the limits of the small cluster used by Giustini et al. According to our results, S(¹D) reacts via two possible reaction mechanisms: (1) addition to the O atom of a water molecule with the formation of H₂OS or (2) insertion into one of the O–H bonds of a water molecule with the formation of HOSH. Both H₂OS and HOSH are stabilized on ice by energy dissipation rather than isomerizing or dissociating into two products as seen in the gas-phase reaction. The interaction with surrounding water molecules affects the entire reaction pathway by stabilizing intermediate species, reducing some barriers, and impeding the only two-product open channel of the gas-phase reaction. S(¹D) can be produced by UV-induced photodissociation of various precursor molecules on the surface of interstellar or cometary ice or by other high-energy processes induced by electrons or cosmic rays also in the ice bulk. Therefore, our results can be of help in elucidating the mysterious sulfur chemistry occurring in the icy mantles of interstellar grains or in cometary nuclei. Furthermore, this study demonstrates that the product branching ratios of gas-phase reactions should not be uncritically used in modeling interstellar ice chemistry.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"844–855 844–855"},"PeriodicalIF":2.9,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00351","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-State Spin-Forbidden Formation of Amide Molecules in the Interstellar Medium","authors":"Amir Mirzanejad,&nbsp; and ,&nbsp;Sergey A. Varganov*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0024010.1021/acsearthspacechem.4c00240","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00240https://doi.org/10.1021/acsearthspacechem.4c00240","url":null,"abstract":"<p >The C₂H₅NO isomers are the simplest family of molecules containing a peptide bond and therefore highly relevant to astrochemistry and astrobiology. We investigate the possible formation mechanisms of the C₂H₅NO amide isomers from the precursors detected in the interstellar medium, focusing on the reaction pathways involving two electronic states with different spin multiplicities. To identify the barrierless reaction pathways, we performed density functional theory and high-level coupled cluster calculations on the reactants, products, intermediates, transition states, and minimum-energy crossing points between singlet and triplet electronic states. Our calculations demonstrate the significance of two-state spin-forbidden pathways in the formation of acetamide, <i>N</i>-methylformamide, and acetimidic acid from acetaldehyde, imidogen, formamide, and methylene. The proposed spin-forbidden pathways provide simple barrierless mechanisms for the formation of the amide isomers in the gas phase, in contrast to the previously proposed reactions catalyzed by surfaces of interstellar icy grains. The proposed mechanisms are consistent with the abundances of acetamide and <i>N</i>-methylformamide observed in Sagittarius B2 North and predict the presence of acetimidic acid in the same region, motivating future observational efforts to identify this molecule in the interstellar medium.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"789–794 789–794"},"PeriodicalIF":2.9,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tire Rubber-Derived Cyclic Amines in Urban Ambient Particulate Matter in Shanghai","authors":"Munila Abudumutailifu,&nbsp;Chengze Li,&nbsp;Haiping Xiong,&nbsp;Sihan Liu,&nbsp;Chunlin Li,&nbsp;Dongmei Cai,&nbsp;Yinon Rudich and Jianmin Chen*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0029110.1021/acsearthspacechem.4c00291","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00291https://doi.org/10.1021/acsearthspacechem.4c00291","url":null,"abstract":"<p >Tire wear compounds (TWCs) and their byproducts have raised increasing environmental and health concerns due to their widespread production and release. In this study, a custom-designed versatile aerosol concentration enrichment system coupled with HPLC-Q-TOF-MS was employed to conduct a nontargeted screening of suspect TWCs in urban PM_2.5, followed by the targeted quantification of ten selected TWCs, providing high temporal resolution data across summer, autumn, and winter in Shanghai. The total TWC concentrations (∑TWCs) exhibited distinct seasonal variations. The highest levels were observed in autumn, with an average concentration of 15.53 ng/m³ (ranging from 1.39 to 58.67 ng/m³), followed by summer with an average of 7.44 ng/m³ (2.22 to 25.39 ng/m³), and the lowest levels observed in winter, with an average of 5.74 ng/m³ (1.56 to 17.83 ng/m³). The seasonal contributions of ∑TWCs were 73.9% in the autumn, 18.6% in the summer, and 7.5% in the winter. The diurnal pattern showed elevated nighttime concentrations compared with morning and evening rush hours. This study marks the first to investigate the diurnal variation in the ratio of <i>N</i>-(1,3-dimethylbutyl)-<i>N</i>′-phenyl-<i>p</i>-phenylenediamine quinone (6PPD-Q) to its parent compound, <i>N</i>-(1,3-dimethylbutyl)-N′-phenyl-<i>p</i>-phenylenediamine (6PPD), in the atmospheric particle phase. The ratio showed a similar daily pattern, peaking in the afternoon and reaching 3.64 in the summer and 6.55 in the autumn, in alignment with temperature and ozone patterns. Correlation analysis showed weak relationships between ∑TWCs and temperature (<i>R</i> = 0.12) as well as a weak negative correlation with humidity (<i>R</i> = −0.04). These findings highlight the need for further research into the toxicological and epidemiological impacts of TWCs, especially considering the heightened levels of nighttime exposure among night workers.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"795–805 795–805"},"PeriodicalIF":2.9,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sectoral Contributions to Primary and Secondary PM2.5 in Regional Airsheds of India","authors":"Alok Kumar,&nbsp;Fahad Imam,&nbsp;Kuldeep Dixit,&nbsp;Ekta Chaudhary,&nbsp;Sumit Sharma,&nbsp;Nimish Singh,&nbsp;Varun Katoch,&nbsp;Shivang Agarwal,&nbsp;Dilip Ganguly and Sagnik Dey*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0033210.1021/acsearthspacechem.4c00332","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00332https://doi.org/10.1021/acsearthspacechem.4c00332","url":null,"abstract":"<p >The exceedance of annual ambient fine particulate matter (PM_2.5) concentrations above the national air quality standard across a large region in India, extending beyond the urban centers, necessitates an airshed approach for effective air quality management. Using over two decades of satellite-derived PM_2.5 concentration data, seasonal wind patterns, and topography, we identified 9–11 major regional airsheds in India and further delineated the local airsheds of nonattainment cities. We separated sectoral contributions to primary and secondary PM_2.5 in each airshed using outputs from a chemical transport model for the National Clean Air Program (NCAP) baseline year. In most airsheds, secondary PM_2.5 constituted a larger share than primary PM_2.5 except for the monsoon season. The domestic sector contributed the most to primary PM_2.5 in most airsheds, while transboundary transport, industry, power, and other sources were the major contributors to secondary PM_2.5. Our results can be used as a reference to assess progress in reducing ambient PM_2.5 levels through the implementation of the NCAP action plan. Our study provides a comprehensive analysis of airsheds in India and underscores the need to control precursor gases, along with primary sources, for effective air pollution mitigation in the context of airsheds.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"806–816 806–816"},"PeriodicalIF":2.9,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Aqueous Environments and the Water Molecule on the Degradation Mechanism of Methylglyoxal Initiated by OH Radicals: A Theoretical Study","authors":"Yali Liu,&nbsp;Bo Shi*,&nbsp;Weigang Wang,&nbsp;Yucong Guo,&nbsp;Yanli Zeng*,&nbsp;Zheng Sun* and Maofa Ge,&nbsp;","doi":"10.1021/acsearthspacechem.5c0001310.1021/acsearthspacechem.5c00013","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00013https://doi.org/10.1021/acsearthspacechem.5c00013","url":null,"abstract":"<p >Carbonyl compounds are ubiquitous in the multiphase system of the atmosphere and have a significant influence on the environment. In order to explore the effects of different environments on the degradation process of pollutants, the reaction mechanisms of methylglyoxal (MGL) and OH radicals in the gas phase and aqueous phase and with/without H₂O were investigated by a theoretical calculation. At 298.15 K, the total rate constants (in units of cm³ molecule^–1 s^–1) of MGL + OH are 6.18 × 10^–11 and 1.73 × 10^–11 in the gas phase and aqueous phase, respectively. Our analysis shows that the initial pathways of the title reaction included two kinds: OH-addition and H-abstraction. The addition pathways are the most favorable, but the contribution of the aldehyde hydrogen abstraction pathways cannot be ignored due to the proportion of H-abstraction pathways could account for 42.85% at 298.15 K in the gas phase, which is just slightly less than 57.15% of OH-addition pathways. In addition, H₂O and aqueous environments inhibited the title reaction. We also evaluated the acute and chronic toxicity of MGL and its reaction products to aquatic organisms at three different trophic levels using the Ecological Structure–Activity Relationships (ECOSAR) program. This research is helpful to reveal the reaction mechanism of MGL in different environments and to assess the risk in aquatic environments.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 4","pages":"934–943 934–943"},"PeriodicalIF":2.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Iron Speciation in Urban Atmospheric Aerosols: Comparison between Thermodynamic Modeling and Direct Measurements","authors":"Chiara Giorio*,&nbsp;Camelia N. Borca,&nbsp;Alexander Zherebker,&nbsp;Sara D’Aronco,&nbsp;Mushtari Saidikova,&nbsp;Hassan Aftab Sheikh,&nbsp;Richard J. Harrison,&nbsp;Denis Badocco,&nbsp;Lidia Soldà,&nbsp;Paolo Pastore,&nbsp;Markus Ammann and Thomas Huthwelker,&nbsp;","doi":"10.1021/acsearthspacechem.4c0035910.1021/acsearthspacechem.4c00359","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00359https://doi.org/10.1021/acsearthspacechem.4c00359","url":null,"abstract":"<p >Metals are important components of atmospheric aerosols for both health and atmospheric reactivity. Coordination chemistry, leading to the formation of metal–ligand complexes, can alter metal solubility and their redox activity in solution; however, such processes have been so far predominantly studied via thermodynamic modeling approaches alone. Such approaches have indicated iron-oxalate complexes as major species of interest in urban environments. In this study, aerosol samples collected in the urban environment of Padua (Italy) are used to compare the speciation picture of iron obtained by thermodynamic modeling with that measured experimentally using X-ray absorption spectroscopy (XAS). The results showed broadly consistent speciation pictures between the two approaches, however, with some quantitative differences probably due to a discrepancy between bulk and single particle chemical composition of the aerosol samples. The XAS results showed the presence of iron-oxalate complexes in the samples, with both Fe(III) and Fe(II), and also suggested that most of the Fe may be mixed with organic matter on an atomic level. The thermodynamic modeling results indicated malonate as an additional important ligand besides oxalate and a potential candidate for explaining the mixed iron-organic nature of the aerosol samples.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"649–661 649–661"},"PeriodicalIF":2.9,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00359","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of the HO•CHC(O)NH2 Radical Intermediate in the Reaction of H + Glycolamide in Solid Para-Hydrogen and Its Implication to the Interstellar Formation of Higher-Order Amides and Polypeptides","authors":"Prasad Ramesh Joshi*,&nbsp; and ,&nbsp;Yuan-Pern Lee*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0040910.1021/acsearthspacechem.4c00409","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00409https://doi.org/10.1021/acsearthspacechem.4c00409","url":null,"abstract":"<p >Glycolamide [HOCH₂C(O)NH₂, GAm], the only isomer of glycine [H₂NCH₂C(O)OH] detected in the interstellar medium (ISM) to date, consists of an inherent peptide bond [C(O)NH] that is fundamental to protein synthesis and the origin of life. Despite its importance in ISM, detailed investigations on the reactivity of GAm under cosmic circumstances remain rather limited. In the present study, we performed the reaction involving H atoms and GAm in solid <i>para</i>-hydrogen (<i>p</i>-H₂) at 3.2 K and observed the exclusive formation of 2-amino-1-hydroxy-2-oxoethyl radical [HO^•CHC(O)NH₂] via H abstraction on the CH₂ moiety of GAm. We successfully characterized the infrared spectra of both <i>Cis–cis</i> (<i>Cc</i>)- and <i>Trans–trans</i> (<i>Tt</i>)-conformers of HO^•CHC(O)NH₂ from the reactions of H + <i>Cc</i>-GAm and H + <i>Tt</i>-GAm in a single experiment; the ratio of <i>Cc</i>:<i>Tt</i> conformers of GAm in the deposited matrix was estimated to be ∼3:2, and, after H abstraction, that of HO^•CHC(O)NH₂ remains approximately the same. In darkness, the increase in the infrared intensities of both conformers of HO^•CHC(O)NH₂ indicated that these radicals were formed from the reaction H + <i>Cc</i>-/<i>Tt</i>-GAm through tunneling, a possible route in dark interstellar clouds. This radical intermediate, HO^•CHC(O)NH₂, may serve as a potential precursor in the formation of higher-order amides bearing a chiral center, including lactamide and glyceramide (glycerol amide), after reactions with ^•CH₃ and ^•CH₂OH, respectively. In addition to the conventional condensation reaction in the process of polymerization for the formation of dipeptides such as malonamide in the dark regions of the ISM, the radical–radical reaction of HO^•CHC(O)NH₂ with NH₂^•CO might serve as an alternative pathway.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"769–781 769–781"},"PeriodicalIF":2.9,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00409","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}